The present invention relates to an ultrasonic probe used for ultrasonic diagnostic apparatus and the like.
Ultrasonic diagnostic apparatus are known which radiate ultrasonic pulse beams into an object to be examined, receiving the echoes which are reflected by the boundary of the structures of organs in accordance with a difference in acoustic impedance, displaying them on a display such as a cathode-ray tube, so that the structure of the organs can be observed from the displayed image. Since they enable the interior of the body to be diagnosed from the exterior, they are widely used.
An ultrasonic probe having an electroacoustic conversion element is used in order to transmit and receive ultrasonic waves. A driving signal of a desired frequency is supplied to the electroacoustic conversion element, whereby ultrasonic beams are radiated from the excited element and the reflected echo is converted into an electrical signal.
Especially, a convex array ultrasonic probe with a tip having a curvature radius of less than 12 mm is very useful for cardiac diagnosis. The probe having a tip of such a small diameter has good operability, because, it enables the tip to be positioned at a part between adjacent ribs for imaging a heart of a patient. In addition, since such a convex array ultrasonic probe has a wide view, it is also useful for abdominal diagnosis. As an example of the convex array ultrasonic probes having a comparatively small curvature radius, one which is described in pp 72 to 76 "Ultrasonics" March, 1972, is conventionally known. However, since the array pitch of the transducer elements in this probe is larger than the radius of the element, it is difficult for this type of probe to realize the lateral resolution and acoustic SN ratio of a high level which are at present required in the medical diagnosis. Incidentally, in the above-described example, the strip-like transducer elements are provided around the shaft of the probe, and the probe therefore has a little different structure from the probe of the present invention which is provided with the transducer elements at the tip thereof.